A light receiving circuit of a laser range finder comprises a photo-sensitive element, a conversion resistance amplifying loop, a main amplification loop, and a one shot circuit. The photo-sensitive element converts a light signal into a current signal. The conversion resistance amplifying loop is connected with the photo-sensitive element for converting the current signal into a voltage signal. The main amplification loop is connected with the conversion resistance amplifying loop for amplifying the voltage signal. The one shot loop is connected with the main amplification loop for shaping the voltage signal into a digital signal by which the range-finding computation is accomplished by the laser range finder.
|
7. A light receiving circuit of a laser range finder, said light receiving circuit comprising:
a photosensitive element for converting a light signal into a current signal; a conversion amplifier connected with said photosensitive element for converting the current signal outputted from the photosensitive element into a voltage signal; a main amplifier connected with the conversion amplifier for amplifying the output voltage signal from the conversion amplifier; and a one-shot circuit connected with the main amplifier for shaping the output voltage signal from the main amplifier into a digital signal by which the range-finding computation is attained by the laser range finder, wherein said main amplifier is a bias stabilized amplifier.
1. A light receiving circuit of a laser range finder, said light receiving circuit comprising:
a photosensitive element for converting a light signal into a current signal; a conversion amplifier connected with said photosensitive element for converting the current signal outputted from said photosensitive element into a voltage signal; a main amplifier connected with the conversion amplifier for amplifying the output voltage signal from the conversion amplifier; a one-shot circuit connected with the main amplifier for shaping the output voltage signal from the main amplifier into a digital signal by which the range-finding computation is attained by the laser range finder; and a bias stabilizing loop which is connected with said conversion amplifier and said main amplifier for enabling the output signal of said conversion amplifier to have a constant bias value.
2. The light receiving circuit as defined in
3. The light receiving circuit as defined in
4. The light receiving circuit as defined in
5. The light receiving circuit as defined in
6. The light receiving circuit as defined in
8. The light receiving circuit as defined in
9. The light receiving circuit as defined in
|
The present invention relates generally to a device of distance measurement based on laser, and more particularly to a light receiving circuit of the laser range finder.
Laser range finder is one of the important devices for measuring the distance. Traditionally, a laser range finder employs a pulse type of the laser transmitter to transmit short laser pulse of about 20 ns onto a target. The reflected laser signal from the target is received by employing a low noise, high sensitivity laser receiver to evaluate the distance by the following formula:
Where L is the distance, C is the speed of light, and Td is time delay between the firing laser pulse and received laser pulse. A precise distance can be obtained by measuring Td according to the formula (1). In order to precisely measure the time delay Td, it needs to increase the transmitted laser power as much as possible or to remove the noise induced by the sunlight in the optical receiver. U.S. Pat. No. 3,644,740 discloses that the signal-to-noise ratio of the receive circuit is improved by controlling the circuit bias on the receiver circuit to get a fixed false alarm. With reference to U.S Pat. No. 4,569,599, a timing control technique is disclosed to detect the distance signal. U.S. Pat. No. 4,770,526 further discloses a technique of amplifying time delay signal to increase the resolution of distance detection. A technique of digital ranging is also disclosed in U.S. Pat. No. 3,959,641 to reduce the threshold value of the optical receiver so as to increase the measured distance.
U.S. Pat. No. 5,612,779 uses an automatic noise threshold determining circuit to get a maximum sensitivity of the laser receiver. A fast charge and slow discharge circuit is also adopted to improve the distance resolution.
In this invention, we will propose a light receiving receiver with a bias stabilized main amplifier followed by a one-shot circuit to get a digital output signal with fixed pulse width. This light receiver circuit can provide a function of maximum sensitivity for the laser receiving circuit, therefore the ranging distance of the laser range finder can also be improved effectively.
The primary objective of the present invention is to provide a laser range finder with light receiving circuit capable of enhancing the sensitivity of the receiving laser signal.
The light-receiving circuit of the laser range finder of the present invention comprises a photosensitive element, a conversion amplifier, a main amplifier, and a one-shot circuit. The photosensitive element converts a received light signal into a current signal, which is then converted into a voltage signal by the conversion amplifier. A main amplifier to get amplification with very high gain then amplifies the output voltage signal of conversion amplifier. The one-shot circuit into a digital signal with fixed pulse width then shapes the output voltage of the main amplifier. This digital signal is then adopted for using in the range-finding process of the laser range finder.
As shown in FIG. 1 and
The photosensitive element 11 is an avalanche photo-detector (APD). The APD is biased with negative bias to get the high internal gain of 100 times and is outputted a current signal when receiving a laser signal reflected by a target.
The conversion amplifier 21 has a trans-impedance amplifier 22, which is formed of two transistors Q201, Q202 and two resistors R203, R205. The trans-impedance amplifier 22 is connected to the photosensitive element 11 for converting the current signal in APD into voltage through a conversion resistor R204. The transistor Q203 and the resistor R207 form an emitter follower 23, which is connected with the trans-impedance amplifier 22. In the meantime, the transistor Q204, the resistors R209, R210 and the capacitor C206 form a common emitter amplifier 25, which is connected with the emitter follower 23. The output signal of the common emitter amplifier 25 is gone through to the bias stabilized main amplifier 31.
The bias stabilized main amplifier 31 has a main amplifier U201, and a plurality of resistors and capacitors. A bias stabilization loops 33 formed of resistor R211 and R212 supplies the stable bias to the main amplifier U201. The direct current bias of the input end of the main amplifier U201 is adjusted by the output of the main amplifier U201 via a low pass filter 35, which is formed of resistor R213 and capacitor C208. As a result, the DC bias of the main amplifier U201 is stabilized and is not affected by the temperature variation induced bias point drift in main amplifier U201.
The one-shot circuit U405 of the preferred embodiment of the present invention is an integrated circuit, which is connected to the bias stabilized main amplifier 31. The one-shot circuit U405 is used for shaping the output signal of the bias stabilized main amplifier 31 into a digital pulse having a predetermined width, and the digital pulses are serially arranged before being transmitted.
The present invention minimizes the voltage drift in main amplifier to enhance the receiving sensitivity of the laser signal reflected from target. In operation, the present invention is connected with the circuit of the laser range finder such that the laser signal reflected from a target is amplified by a high magnification into the electronic signal and is shaped by the one- shot loop. According to the electronic signal, the laser range finder can measure distance between a target and range finder.
Hung, Chih-Wei, Chien, Pi-Yao, Lai, I-Jen, Huang, Jui-Feng
Patent | Priority | Assignee | Title |
7599045, | Jan 25 2006 | Asia Optical Co., Inc. | Method for eliminating internal reflection of range finding system and range finding system applying the same |
7755025, | Nov 14 2002 | DIGIMEDIA TECH, LLC | Detecting and thwarting content signals originating from theatrical performances |
8148673, | Nov 14 2002 | DIGIMEDIA TECH, LLC | Detecting and thwarting content signals originating from theatrical performances |
8309926, | May 02 2008 | Pulsed-laser beam detector with improved sun and temperature compensation | |
9400326, | Oct 06 2011 | Laser Technology, Inc.; Kama-Tech (HK) Limited | Non-saturating receiver design and clamping structure for high power laser based rangefinding instruments |
9772399, | Nov 22 2013 | UTAC, LLC; UATC, LLC | LiDAR scanner calibration |
9971024, | Nov 22 2013 | UTAC, LLC; UATC, LLC | Lidar scanner calibration |
Patent | Priority | Assignee | Title |
3644740, | |||
3959641, | Dec 05 1974 | The United States of America as represented by the Secretary of the Army | Digital rangefinder correlation |
4569599, | Apr 28 1982 | MITEC MIKROELEKTRONIK MIKROTECHNIK INFORMATIK GMBH | Method of determining the difference between the transit times of measuring pulse signals and reference pulse signals |
4678323, | Jul 20 1984 | Canon Kabushiki Kaisha | Distance measuring devices and light integrators therefor |
4681432, | Apr 01 1983 | Canon Kabushiki Kaisha | Photo-electric converting device |
4770526, | Nov 13 1985 | Messerschmitt-Boelkow-Blohm GmbH | Ranging method and apparatus |
5357331, | Jul 02 1991 | Lockheed Martin Corp | System for processing reflected energy signals |
5396510, | Sep 30 1993 | Honeywell Inc. | Laser sensor capable of measuring distance, velocity, and acceleration |
5612779, | Jan 19 1995 | KAMA-TECH HK LIMITED | Automatic noise threshold determining circuit and method for a laser range finder |
5767953, | Apr 12 1993 | Lawrence Livermore National Security LLC | Light beam range finder |
6103546, | Mar 13 1998 | National Science Council | Method to improve the short circuit current of the porous silicon photodetector |
6115114, | Apr 12 1996 | HOLOMETRICS, INC | Laser scanning system and applications |
6259321, | Nov 23 1999 | MTEKVISION CO , LTD | CMOS variable gain amplifier and control method therefor |
6310682, | Jul 06 1999 | Quarton, Inc.; Segnetron Israel, Ltd. | System and method for laser range finder |
Executed on | Assignor | Assignee | Conveyance | Frame | Reel | Doc |
Nov 20 2000 | LAI, I-JEN | ASIA OPTICAL CO , INC | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 011838 | /0325 | |
Nov 20 2000 | CHIEN, PI-YAO | ASIA OPTICAL CO , INC | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 011838 | /0325 | |
Nov 20 2000 | HUANG, JUI-FENG | ASIA OPTICAL CO , INC | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 011838 | /0325 | |
Nov 20 2000 | HUNG, CHIH-WEI | ASIA OPTICAL CO , INC | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 011838 | /0325 | |
Feb 12 2001 | Asia Optical Co., Inc. | (assignment on the face of the patent) | / | |||
Jul 10 2012 | ASIA OPTICAL CO , INC | HIGH NETWORK LIMITED, LLC | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 028529 | /0988 | |
Aug 16 2012 | ASIA OPTICAL CO , INC | ASIA OPTICAL INTERNATIONAL LTD | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 028842 | /0757 | |
Nov 06 2013 | HIGH NETWORK LIMITED, LLC | ASIA OPTICAL CO , INC | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 031551 | /0275 | |
Sep 14 2020 | ASIA OPTICAL INTERNATIONAL LTD | RANGING OPTICS LLC | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 054139 | /0541 |
Date | Maintenance Fee Events |
Jun 20 2006 | STOL: Pat Hldr no Longer Claims Small Ent Stat |
Jul 28 2006 | M1551: Payment of Maintenance Fee, 4th Year, Large Entity. |
Jul 28 2010 | M1552: Payment of Maintenance Fee, 8th Year, Large Entity. |
Jun 09 2014 | M1553: Payment of Maintenance Fee, 12th Year, Large Entity. |
Date | Maintenance Schedule |
Jan 28 2006 | 4 years fee payment window open |
Jul 28 2006 | 6 months grace period start (w surcharge) |
Jan 28 2007 | patent expiry (for year 4) |
Jan 28 2009 | 2 years to revive unintentionally abandoned end. (for year 4) |
Jan 28 2010 | 8 years fee payment window open |
Jul 28 2010 | 6 months grace period start (w surcharge) |
Jan 28 2011 | patent expiry (for year 8) |
Jan 28 2013 | 2 years to revive unintentionally abandoned end. (for year 8) |
Jan 28 2014 | 12 years fee payment window open |
Jul 28 2014 | 6 months grace period start (w surcharge) |
Jan 28 2015 | patent expiry (for year 12) |
Jan 28 2017 | 2 years to revive unintentionally abandoned end. (for year 12) |